Process Experiment: Can you Ferment a Sour Beer and a Clean Beer Side by Side?

As previously noted in my sour beer post, I love sour beer. After brewing my first sour, and doing a little sample, I was freaking stoked! I could not believe that I had produced something even remotely similar to the sours I’ve enjoyed over the years. With the knowledge that I wasn’t going to be able to enjoy this beer for another 6-8 months, I figured it was time to brew more sour beers so I would have a steady supply sometime in the future. I didn’t want to sacrifice my fermentation chamber for another three weeks at 80 degrees to get 5-10 gallons of beer that would be ready a year from now. Searching the internet I found mixed results on whether or not you can ferment sour and clean beer in the same chamber, let alone at the same time. Since no definitive answer could found I decided this should be my next process experiment. Around the time of deciding to brew this I was listening to a lot of Jamil’s old shows on the brewing network, and, became really interested in trying the Roeselare blend from wyeast. After deciding to try this blend, I settled on the recipe from the first sour, and chose to do a 10 gallon split batch between WY3763 and a normal Trappist ale. The Trappist ale would be fermented side-by-side with the sour and subsequently entered into the NHC to determine if BJCP judges noted this beer as having any off flavors consistent with cross contamination. Also, with the high FG, I decided to use the Trappist ale to top off my sour which would eventually be transferred to a Hungarian oak barrel for aging.


To determine if a clean beer can be fermented in the same chamber, side by side with a “non-clean” beer without becoming contaminated.


Brew a 10 gallon batch split into two 6 gallon PET carboys, fermented in the same fermentation chamber. One beer inoculated with a sour blend, the other inoculated with a traditional brewers yeast. The non soured beer will be entered into the first round of 2016 National Homebrewers Conference competition to determine if BJCP sanctioned judges detect off flavors associated with cross contamination.

 Recipe: Ouder

Volume (gallons) 11
O.G. 1.064
F.G (estimated) 1.013
IBU 15
SRM 17.0
ABV 6.7%
Grains Amount (lbs) PPG SRM (degL)
Avangard Pilsner 19 1.037 2.0
Weyermann CaraMunich II 4 1.034 46.0
Briess Red Wheat 4 1.037 2.5
Special B 1 1.031 147.0
Hops Amount (oz) Alpha Time
Northern Brewer 1.76 6.8 FWH
Yeast Temp (f) Attenuation (apparent)
WY3763 Roeselare Ale Blend 70 80%
WLP500 Monastery Ale Yeast 70 78%
Steps Temp (f) Time (min) ph
Saccharification 150 60 5.2
Water (ppm) Ca Mg Na Cl SO4 Bicarbonate
Bru’n Water W. Flanders Boiled 80.2 9.1 28.8 74.3 73.9 145


The night before brewing I purchased my ingredients and water and the following morning adjusted the water to Bru’n water West Flanders (boiled), and mashed in.

I was so close to my mash temp of 152!

I nearly hit my mash ph of 5.2 as predicted and proceeded to lautering.

I boiled for 75 min and chilled the wort super fast.

After chilling the wort, I split both batches into separate carboys, hit them with 60 seconds of oxygen, and placed them in my fermentation chamber at 70 degrees.

12 hours post pitch for the Roeselare and 0 hours for the WLP500 (my starter wasn’t properly planned) I guess this experiment will really test this variable.

24 hours post pitch WLp500, 36 hours post pitch WY3763. I cleaned up the 500 and gave it two drops of fermcap-s, even more room for contamination (side note: even though I love them, the six gallon capacity of these PET carboys is killing me!).

Day 9: Took a reading of the WLP500, 1.016, third day in a row after increasing the temp to 75 from day 5-9. On day 10 WLP500 was removed from the fermentation chamber and moved to the fridge to crash and fine. The WY3763 was left in the chamber alone and bumped up to 80 over the next few days. After two weeks the sour beer was then transferred to my 6 gallon Hungarian Oak barrel and topped off with some of the WLP500 beer. It will age in the barrel for around 6 months.

The WLP500 was fined and kegged, ready to be served to some NHC judges! I entered it into the category of 21B Belgian Dubbel (BJCP style 26B). Given the long lag time between bottling and evaluation at room temp (still a sore subject for me), any infection should be clearly noticeable to the judges. In my opinion though it’s a pretty damn good beer.



This being my first competition I was fairly apprehensive and spent many days refreshing the results page on the NHC site. My scores actually arrived in the mail before the results were posted. I got a 38 on my dunkles bock which I was somewhat disappointed with as I felt this beer was closer to a 42, oh well the judges gave me great feedback (like racking off the trub before going into the fermentor Marshall 🙂 )! The disappointment was short lived though, when I got to the dubbel score sheet I was happy to see that beer received a 41/50. Reading the score sheets there were no references to any off flavors that would be associated with sour beer. No notes of brett, no sourness, nothing! I actually had one bottle of this left over that I drank while reading the score sheet, even looking hard for any hint of off flavors there were none. I think it’s safe to say you can ferment a sour beer and a clean beer in the same chamber without fear.

Cheers and if you have any ideas for future comparisons please feel free to contact us. Our email address is now on the authors page.

7 thoughts on “Process Experiment: Can you Ferment a Sour Beer and a Clean Beer Side by Side?

  1. I think the issue of cross-contamination between clean/sour fermentations is more an issue of barrels than glass/plastic carboys. I age clean/sour/funky/everything in between in glass carboys all the time without trouble.

    The issue that Jamil found was that respiration of Brett barrels allowed the Brett to essentially “burrow” through the barrels and “jump” to nearby clean barrels. Unless you’re keeping mixed barrels very close to each other and don’t spray sour beer all over the place you’re probably okay 🙂


  2. Thats a great score for your first homebrew competition, so id be proud of that. I wish you had more dubbel that i could try. Last year i entered denver i got a 41 with my belgian golden strong, and got goose egged. this year was different. keep up the good work.

    Liked by 1 person

      1. That is fantastic! Thanks for the feedback on my score. Honestly I really don’t have a context for what a good/great score is. What did you get for the 1st place if you don’t mind me asking?


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